During posthypnotic amnesia, subjects have difficulty in remembering events and experiences that transpired during hypnosis until the experimenter administers a prearranged cue to lift or reverse the amnesia. This phenomenon is one of the central phenomena in the domain of hypnosis; thus, systematic study of posthypnotic amnesia may lead to important insights about the nature of hypnosis itself. Moreover, because this impairment in memory can be easily and reliably induced and lifted in normal human subjects without any hazard, it may serve as a laboratory model for the experimental study of the processes underlying the pathological amnestic states observed in the clinic, and shed light on factors involved in normal remembering and forgetting. Although a great deal of progress has been made recently in understanding the nature of posthypnotic amnesia, little is known about the conditions under which the memory block can be overcome (that is, without resort to the prearranged reversibility cue). A series of studies is proposed which will assess the effectiveness of various procedures in breaching posthypnotic amnesia: (1) the contribution of remission of amnesia and reminiscence effects to the spontaneous recovery of the affected memories; (2) the time-course of spontaneous recovery from posthypnotic amnesia, and the effects of distraction, effort, and free association on that recovery; (3) the effects on posthypnotic memory of the reinduction of the hypnotic state; (4) a comparison of recall and recognition measures of amnesia; and (5) the possibility that specific and generic reminders of forgotten events will trigger the recall of other, unpresented material. The results of these experiments will greatly expand our knowledge of the cognitive mechanisms underlying both posthypnotic amnesia and, by extension, clinical amnestic states. Specifically, these experiments may suggest alternate, effective means of treating clinical amnesia.